http://neotokyohq.com/NeoTokyo is a HL2 mod that I have been playtesting it is really amazing looking and one of the better mods/games on the source engine

from the NT site
about neotokyo

NEOTOKYO is a first person shooter that provides a visceral & realistic combat experience in a rich futuristic setting. It is greatly influenced by our admiration for Masamune Shirow (GHOST IN THE SHELL) and Katsuhiro Otomo (AKIRA), and has been in production since October 2004. To play NEOTOKYO you will need to have a STEAM account, and own the game HALFLIFE 2 or any game that gives you the Source SDK ...

story

NEOTOKYO takes place about 30-40 years from now in a Japan that has drifted into social/political strife due to the inevitable stresses that come from changing times. The Japanese government is grappling with intensified external (Asia geopolitics) and internal (economic/social) problems, and there is mounting pressure from within Japan to return to the days when it exerted influence through military power and strength. A failed legislative push to alter the Japanese Constitution (allowing the Japanese military to engage in offensive actions outside of the country) leads to an attempted military coup by members of Japan's armed forces (GSDF). The coup fails, but was very close to succeeding. In an effort to suppress further coup attempts, Japan's Prime Minister forms a branch inside the Interior Ministry's National Security Forces (NSF) called GROUP SIX. They answer directly to the Prime Minister and are sworn to protect the Japanese Constitution at all costs. They immediately begin to hear rumours of a rogue element of the GSDF Special Forces (JINRAI) maneuvering for a second coup attempt. These JINRAI are Special Operations Group 43 (SOG43), fierce nationalist loyal to their love of country, and a desire to put Japan back into a position of strength and power.